Question
A space station orbits the Earth at a distance of \(7000 \mathrm{~km}\) from the Earth’s centre. It makes 15 orbits in every 24 -hour period.
What is the speed of the space station in its orbit?
A \(2900 \mathrm{~km} / \mathrm{h}\)
B \(4400 \mathrm{~km} / \mathrm{h}\)
C \(8800 \mathrm{~km} / \mathrm{h}\)
D \(27000 \mathrm{~km} / \mathrm{h}\)
▶️Answer/Explanation
Ans: D
Question
What is the definition of the Hubble constant?
A the ratio of the speed at which a galaxy is receding from the Earth to its distance from the Earth
B the value of the change in wavelength of the galaxy’s starlight due to redshift
C the constant used to represent the rate of expansion of the Universe in all directions
D the estimated constant equal to the age of the Universe
▶️Answer/Explanation
Ans: A
Question
The Sun transfers energy to the Earth through electromagnetic radiation.
What are two of the parts of the electromagnetic spectrum to which most of the energy belongs?
A gamma rays and \(X\)-rays
B infrared radiation and visible light
C microwaves and visible light
D radio waves and microwaves
▶️Answer/Explanation
Ans: B